Bees are busier than ever as disease besieges colonies

California almond growers have their orchards pollinated by bees, some of which are trucked across the country afterward for work on the East Coast. The trip could be a factor as bee populations decline yearly.
(U.s. Department Of Agriculture)

Network News

In normal times, David Hackenberg would begin trucking his 20 million honeybees from the almond orchards of California to the orange groves of Florida this week.

Instead, after a month working the almond blossoms on the West Coast, his exhausted pollinators will get some rest and relaxation in the Georgia woods before the East Coast apple blossoms summon them to work once more next month.

These are not normal times for bees, or for commercial beekeepers, so Hackenberg's pollinators will skip the citrus gig to reduce their exposure to pesticides and get some rest. "Everybody is seeing [bee] losses this winter," said Hackenberg, of Lewisburg, Pa. "This was probably the worst year ever."

More than three years after beekeepers starting seeing the sudden disappearance of hive populations, scientists have yet to find the cause -- let alone the fix -- for a condition called colony collapse disorder (CCD). Meanwhile, the commercial beekeeping industry is struggling to provide pollination services to the nations' farmers. One-third of food crops rely on insect pollination.

A recently published survey suggests that hive losses have stabilized at around 30 percent a year, but that high figure is based on last winter's data. Anecdotally, the losses have climbed this winter, although a formal tally won't occur until the spring.

"I am very concerned about this year based on what we have seen in California and other parts" of the United States, said Jeffery S. Pettis, research leader for the Agricultural Research Service's honey bee laboratory in Beltsville. He has visited the almond farms of California three times this winter to assess losses. The state's growers produce 80 percent of the world's almond crop and require 1.5 million of the nation's estimated annual peak of 2.5 million managed hives. In the halcyon days after World War II, there were more than 5 million managed hives in the United States, and countless feral honeybee colonies that are now gone.

Hackenberg said he and other major commercial beekeepers have seen "50 percent or better" losses since late fall and in the winter, when bees typically are clustered in a warm and fuzzy ball within the hive. "We started seeing losses in late October, early November -- and they just kept going through the middle of January," he said. Some of the losses will be made up by beekeepers splitting one strong hive into two weaker ones.

Eighty percent of his afflicted hives showed signs of CCD, Hackenberg said. With the condition, foraging worker bees don't return to a hive even if a full brood is waiting to hatch. One theory is that the foragers, knowing they are sick, fly off to die rather than compromise the hive.

Scientists at first figured that they would identify a single virus or pest responsible for the collapse after the phenomenon surfaced in fall 2006, and an early suspect was a bloodsucking parasite called the Varroa mite. If bees were the size of humans, said Jerry Hayes, of the Florida Department of Agriculture, the mite would be as large as a rat. Another was a pathogen named Israeli acute paralysis virus, which showed up in collapsed colonies.

After three years of research, scientists think the cause is not a single factor but a cocktail of maladies that together weaken and sicken the bees. "We know CCD bees get all the pathogens causing the symptoms; it doesn't leave answered what's the underlying cause," said Dennis vanEngelsdorp, Pennsylvania's acting state apiarist.

Environmental stress, including pesticides and the strain of being trucked across time zones and climates, may also be a factor. Poor nutrition may also contribute, a diet of corn syrup or the nutritionally inferior nectar or pollen of crops such as cranberry, cucumbers or melons.

"I thought we could find the smoking gun, make a recommendation and save the industry, and we have not been able to do that," Hayes said.